Palindromic prime concatenated with next palindromic prime is a prime.

Terms

a(0) =2a(1) =31513a(2) =32423a(3) =37273a(4) =37573a(5) =78887a(6) =1120211a(7) =1123211a(8) =1160611a(9) =1178711a(10) =1262621a(11) =1273721a(12) =1311131a(13) =1335331a(14) =1444441a(15) =1548451a(16) =1557551a(17) =1600061a(18) =1761671a(19) =1826281a(20) =1884881a(21) =3233323a(22) =3558553a(23) =3621263a(24) =7057507a(25) =7084807